/* clock example: frequency of primes */
#include <stdio.h>
#include <time.h>
#include <math.h>

int frequency_of_primes(int n) 
{
  int i, j;
  int freq = n-1;
  for (i = 2; i <= n; ++i) 
    for (j = sqrt(i); j > 1; --j) 
      if (i%j == 0) {
        --freq; 
        break;
      }
  return freq;
}

int main()
{
  int f;
  int t;
  printf("Calculating...\n");
  f = frequency_of_primes(99999);
  t = clock();
  printf("The number of primes lower than 100,000 is: %d\n", f);
  printf("It took me %d clicks (%f seconds).\n", t, ((float)t)/CLOCKS_PER_SEC);
  return 0;
}
